The present invention relates to a new and improved tool arrangement or apparatus for a bending press.
In its more particular aspects, the tool arrangement of the present development is intended for use with a bending press equipped with a displaceable ram, an elastically yielding hydraulic cushion within the ram and a work table. A segmental tool holding fixture is mounted in the hydraulic cushion and a tool support is secured to the work table. This tool support comprises a bottom die with which cooperates a segmental first tool arranged in the tool holding fixture.
It has been suggested for a bending press as known, for example, from German Pat. No. 2,522,882, to form the tool which is elastically yieldably supported at an oil cushion from a number of partial elements which are arranged in juxtaposition and which are vertically displaceable independently of each other. Only those partial elements which indirectly or directly engage the workpiece are displaced towards the oil cushion under load.
The proposed design of the bending press ensures for a uniform distribution of pressure at the ram tip throughout the entire bending length of the workpiece, whereby high precision in the working operation and faultless bending results are obtained.
It happens rather frequently that bending operations have to be performed in accordance with a predetermined program according to which an operative or work step, but with the use of a further, different tool, is required to be performed between the individual operating or working steps where there is used the tool present in the tool arrangement. For this purpose the tool inserts have to be exchanged against others. The suggested bending press is thus unsuitable for such use, since the exchange operations are cumbersome and time-consuming and, above all, disadvantageously affect series or mass production manufacturing operations.
In another bending work installation as known, for example, from German Patent Publication No. 2,652,886, an auxiliary tool is associated with a main or primary tool. By means of positioning or control cylinders that one of the tools can be selectively placed into operation which is required for performing a predetermined bending operation. An upper portion of the two-piece auxiliary tool is fixedly connected to the main tool while a lower portion of the auxiliary tool is positively or form-lockingly and vertically displaceably mounted in a guiding member or bracket. The two portions of the auxiliary tool are designed in a mirror-image relationship, for example, in a saw-tooth shape or meander-like configuration. In their rest or idle position they are matchingly interengaged. The auxiliary tool is brought into the work or operative position by downwardly and laterally displacing the lower tool portion in the same plane by means of the positioning or control cylinders and the guiding members such that for the transmission of the ram force the interrupted lower surfaces of the upper fixed tool portion and the interrupted upper surfaces of the lower displaceable tool portion are positioned on top of each other.
It is a disadvantage of this known installation as described hereinbefore that, in addition to the involved and expensive design of the two parts or members of the auxiliary tool, either the main tool or the two-piece auxiliary tool only can be placed into an operative or into an idle or rest position over the entire width of the multiple tool. It is required, for example, for the U-shaped bending of sheet metal pieces bent at all sides, to substitute the multiple tool of a given length with a multiple tool of a different length.